A significant fraction of power of satellites signals such as a Global Navigation Satellite System (GNSS) signal may be lost in urban and indoor environments where satellites signals are frequently blocked. Blocking satellite signals weakens coverage in urban and indoor environments, and loss of power degrades performance in low signal-to-noise ratio (SNR) environments. Degraded performance in low SNR environments may prevent or minimize an ability of an authentication system to validate that a position computation or an assertion based on a position is bona fide.